A gas turbine includes a compressor, a combustor, and a turbine. Here, air which is taken from an air inlet is compressed by a compressor so as to become hot and pressurized compressed air, a fuel is supplied to the compressed air in a combustor so that the fuel and the air are burned, the hot and pressurized combustion gas drives a turbine, and then a power generator connected to the turbine is driven. In this case, the turbine is formed by alternately arranging a plurality of turbine vanes and a plurality of turbine blades inside a wheel chamber, and the turbine blades are driven by a combustion gas, so that an output shaft connected to the power generator is rotationally driven.
Further, the turbine vane has a structure in which a shroud is fixed to an end of a vane body in the length direction. Then, cooling air is introduced from each shroud into the vane body so as to cool the inner wall surface of the vane body, and the cooling air is discharged from a cooling hole formed in the vane body to the outside so that the cooling air flows along the outer wall surface of the vane body, thereby cooling the outer wall surface of the vane body.
As such a turbine vane, for example, examples are disclosed in Patent Literatures 1 and 2 below. With regard to a steam outlet flow for a rear cavity of a blade profile part disclosed in Patent Literature 1, steam flowing to an outer wall impingement-cools an outer wall surface through an impingement plate, flows into a cavity of a turbine vane, flows into an inner wall, impingement-cools an inner wall surface through an impingement plate, and returns through a returning cavity. Further, with regard to a turbine vane disclosed in Patent Literature 2, cooling air flows from an impingement plate near each shroud into a cavity of the shroud so as to cool the cavity, flows from the impingement plate of a vane body into the cavity of the vane body so as to cool the cavity, and is discharged from a film-cooling hole to the outside.